The Common nighthawk is one of the last migrants to arrive in the South Okanagan, often seen flying over the city in early evening.

Migration is in the air

This month continues with the “miracle” of bird migration. While we don’t live on one of the three major North American flyways – the routes that most birds use on their twice yearly trips – we do get a large number of migrants passing through the Valley or arriving here to spend the summer and raise the next generation of their species.

Although we often think of ducks and geese when we mention bird migration, migratory birds can be found amongst all types of birds from the smallest (hummingbirds) to some of the largest (swans). It is common to think of birds flying north in the spring and then repeating the same journey in reverse in the fall, but bird migration is actually far more complex. To be sure, some birds do exactly that – take a more or less straight forward route north and reverse that route in the fall. Sandhill Cranes are a fairly typical example of birds that fly pretty much north from their wintering grounds and follow the reverse course later in the year. Hence we can see cranes overhead in the Okanagan both spring and fall. But many birds take complex paths and their northern route may be totally different from their southern route. Making our assumptions about migration even more tenuous are those birds that migrate across the continent rather than north-south and still others that migrate altitudinally – that is they go higher in the mountains in the summer and lower in the winter. Local examples of these birds are Clark’s Nutcracker, Pine Grosbeaks and some finches. Other birds might not come readily to mind as migrants but do migrate, such as many of the hawks. Swainson’s Hawk occurs in the Okanagan Valley during the summer but in the fall migrates all the way to southern Argentina.

Adding to the complexity of migration is the variation in timing as to when various birds migrate. Bird migration is a long drawn-out process. “Spring” migration is as early as late February or early March for some species that come to our Valley (Say’s Phoebe) or as late as June for others (Common Nighthawk) with May being the busiest month for migrants. For some birds, such as hummingbirds, the males migrate several weeks earlier than the females, arriving in their breeding areas ahead of the ladies in order to establish territories where they will compete for a mate.

The “fall” migration is equally spread out – male hummingbirds are often gone from our Valley by early August; at this same time the shorebirds are already beginning to pass through the Valley on their way south from their northern breeding grounds. September and October see large numbers of birds passing through but other species may “hang around” until late October or even November before heading south.

The next time you spot a bird in your summer garden that you know is gone in the winter reflect for a moment on the incredible journeys that many of these undertake. Facing all kinds of hazards, from predators to bad weather to man-made obstacles such as communication towers, migratory birds often fly thousands of miles (some as many as 5,000 miles one way) and sometimes when they reach their destination, their habitat has, sadly, been adversely impacted by human activity.